Band gaps of wurtzite Sc<i>x</i>Ga1−<i>x</i>N alloys

Tsui, Hei Chit Leo; Goff, Lucy E.; Rhode, Sneha; Pereira, S.; Beere, Harvey E.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A.; Moram, M. A.

doi:10.1063/1.4916679

Cited by 15 publications

(23 citation statements)

References 28 publications

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“…Sc x Ga 1-x N films grown using molecular beam epitaxy (MBE) under nitrogen-rich conditions showed a transition from the wurtzite to the cubic structure at approximately x = 0.17 14 whereas the films grown under metal-rich conditions remained in the wurtzite structure up to x = 0.26, consistent with a recent high quality theoretical calculation 13,15 . Recent data from high quality wurtzite Sc x Ga 1-x N films showed that the optical band gap increases with increasing Sc content, consistent with recent theoretical calculations 13,16 ; a decrease in the band gap of Sc x Ga 1-x N with increasing x (as reported previously 14,17 ) only occurs with increasing Sc content in the presence of nanoscale inclusions 16 .…”

Section: Introductionsupporting

confidence: 70%

“…(2), where the band gaps of Sc x Ga 1-x N films have been presented in Ref. 16 and the band gap of AlN have been known as 6.2 eV 13,42 . Therefore, a band alignment diagram can be constructed, as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…The composition of the film was controlled by varying the Sc flux by controlling the effusion cell temperature, while the Ga flux was kept constant. The Sc flux varied between 0 nA and 2 nA, which corresponds to a Sc content x of 0 and 0.15 according to previous Rutherford backscattering measurements 16 . The film thicknesses (~ 5 nm and ~100 nm) were estimated from the growth rate reported in Ref.…”

Section: Methodsmentioning

confidence: 99%

“…Among them, XPS is the most commonly used technique as it allows direct measurement of the valence band edge relative to the Fermi level along with the core level binding energy, whereas simulation and fitting are needed for other techniques [21][22][23] . Since the Sc x Ga 1-x N films grown on MOVPE AlN have better crystal quality, the for Sc x Ga 1-x N/AlN heterojunction is of interest for its potential devices 16 . Therefore, this study aims to investigate the influence of Sc to the valence band offsets of the Sc x Ga 1-x N/AlN heterojunction using XPS.…”

Section: Introductionmentioning

confidence: 99%

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Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Tsui¹,

Goff²,

Palgrave³

et al. 2016

J. Phys. D: Appl. Phys.

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The valence band offsets of Sc x Ga 1-x N/AlN heterojunction were measured by X-ray photoelectron spectroscopy (XPS) and were found to increase from 0.42 eV to 0.95 eV as the Sc content x increased from 0 to 0.15. The increase in valence band offset with increasing x is attributed to the corresponding increase in spontaneous polarisation of the wurtzite structure. The Sc x Ga 1-x N/AlN heterojunction is type I, similar to other III-nitride-based heterojunctions. The results also indicated that a type II staggered heterojunction, which can enhance spatial charge separation, could be formed if Sc x Ga 1-x N is grown on GaN.

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Section: Introductionsupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Tsui¹,

Goff²,

Palgrave³

et al. 2016

J. Phys. D: Appl. Phys.

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“…Both Sc x Ga 1-x N and Sc x Al 1-x N alloys are of growing technological interest in this regard and are created by alloying ScN with GaN or AlN respectively [5,[14][15][16][17][18][19][20][21][22][23][24]. ScN is an indirect gap semiconductor with the rock-salt structure and has been of interest recently for thermoelectric device applications [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Composition measurement of epitaxial Sc_xGa_1−xN films

Tsui

Goff

Barradas

et al. 2016

Semicond. Sci. Technol.

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Four different methods for measuring the compositions of epitaxial Sc x Ga 1-x N films were assessed and compared to determine which was the most reliable and accurate. The compositions of epitaxial Sc x Ga 1-x N films with 0 ≤ x ≤ 0.26 were measured directly using Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS), and indirectly using c lattice parameter measurements from X-ray diffraction and c/a ratio measurements from electron diffraction patterns. RBS measurements were taken as a standard reference. XPS was found to underestimate the Sc content, whereas c lattice parameter and c/a ratio were not reliable for composition determination due to the unknown degree of strain relaxation in the film. However, the Sc flux used during growth was found to relate linearly with x and could be used to estimate the Sc content.

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The effect of metal‐rich growth conditions on the microstructure of Sc_xGa_1−xN films grown using molecular beam epitaxy

Tsui

Goff

Barradas

et al. 2015

Physica Status Solidi (a)

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This is a repository copy of The effect of metal-rich growth conditions on the microstructure of ScxGa1-xN films grown using molecular beam epitaxy.White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/93558/ Version: Accepted Version Article:Tsui, H.C.L., Goff, L.E., Barradas, N.P. et al. (7 more authors) (2015) The effect of metal-rich growth conditions on the microstructure of ScxGa1-xN films grown using molecular beam epitaxy. physica status solidi (a), 212 (12). 2837 -2842. ISSN 1862-6300 https://doi.org/10.1002/pssa.201532292 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. AbstractEpitaxial ScxGa1-xN films with 0 x 0.50 were grown using molecular beam epitaxy under metal-rich conditions. The ScxGa1-xN growth rate increased with increasing Sc flux despite the use of metal-rich growth conditions, which is attributed to the catalytic decomposition of N2 induced by the presence of Sc. Microstructural analysis showed that phase-pure wurtzite ScxGa1-xN was achieved up to x = 0.26, which is significantly higher than that previously reported for nitrogen-rich conditions, indicating that the use of metalrich conditions can help to stabilise wurtzite phase ScxGa1-xN.Keywords: ScGaN, molecular beam epitaxy, TEM PACS codes: 61.66Dk, 68.55Nq, 81.05Ea, 81.15Hi 1 Introduction Wurtzite-structure III-nitrides are of interest for optoelectronic and high power electronic applications. These semiconductors include AlN, GaN and InN and their alloys, which have direct band gaps of 6.2 eV, 3.4 eV and 0.7 eV respectively [1][2][3][4] and are therefore able to emit light across the ultraviolet, violet and red spectral regions. However, current state-of-the-art optoelectronic devices suffer from poor internal quantum efficiencies, partly due to the lattice mismatch with the substrate or between layers leading to high dislocation densities and in-plane stresses [5]. Therefore, it is of interest to develop new wurtzite-structure nitride semiconductors with different lattice parameter-band gap relationships, such as alloys between GaN and ScN.

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Band gaps of wurtzite ScxGa1−xN alloys

Cited by 15 publications

References 28 publications

Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Composition measurement of epitaxial Sc_xGa_1−xN films

The effect of metal‐rich growth conditions on the microstructure of Sc_xGa_1−xN films grown using molecular beam epitaxy

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Band gaps of wurtzite ScxGa1−xN alloys

Cited by 15 publications

References 28 publications

Valence band offsets of ScxGa1−xN/AlN and ScxGa1−xN/GaN heterojunctions

Valence band offsets of ScxGa1−xN/AlN and ScxGa1−xN/GaN heterojunctions

Composition measurement of epitaxial ScxGa1−xN films

The effect of metal‐rich growth conditions on the microstructure of ScxGa1−xN films grown using molecular beam epitaxy

Contact Info

Product

Resources

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Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Composition measurement of epitaxial Sc_xGa_1−xN films

The effect of metal‐rich growth conditions on the microstructure of Sc_xGa_1−xN films grown using molecular beam epitaxy